1. Field of the Invention
The present invention relates to a light-transmissive input device capable of transmitting light and performing an input operation, and more particularly, to a light-transmissive input device and a method of manufacturing the same capable of enhancing a light-shielding function of a decorative area covering a wiring area and of increasing a shielding function of the wiring area.
2. Description of the Related Art
A light-transmissive input device is provided in a portable electronic device or the like. The light-transmissive input device is configured with a light-transmissive base material as a main body and is provided at a position covering a display device of a liquid crystal display panel or the like. An input operation may be performed by touching a display area of a display screen with a finger or the like while seeing through a display image.
As a method of detecting the input operation, an electrostatic capacitive type or a contact type is employed. In the electrostatic capacitive type, a light-transmissive X conductive layer extending in the X direction and a light-transmissive Y conductive layer extending in the Y direction oppose each other in a detection area, and a potential is alternately applied to the X conductive layer and the Y conductive layer. When a finger of a person substantially at a ground potential approaches, an electrostatic capacitance is formed between the X and Y conductive layers and the finger, and the voltage or current when the potential is applied to the X or Y conductive layer is changed. By detecting this change, the position that the finger approaches is detected. In the contact type, transmissive conductive layers that oppose each other are provided in a detection area, and a voltage is alternately applied to the conductive layers. When the one conductive layer pressed by a finger or a pin comes in contact with the other conductive layer, the position is detected as a change in resistance or the like.
The light-transmissive conductive layers are formed in the detection area, and display contents of the display device may be seen though the area. In the periphery of the detection area, a disposition area of a wiring pattern electrically connected to each of the conductive layers is provided. Regarding this wiring area, the following problems are present.
(a) When light from the display device is emitted from the rear, the wiring area in the periphery of the detection area needs to be covered. In a coordinate input device described in Japanese Unexamined Patent Application Publication No. 2005-173970, on the rear side of an upper light-transmissive substrate positioned at the uppermost surface, a decorative printing layer is formed in a frame shape, and the decorative printing layer covers the peripheral part of the input device.
However, in order for the decorative printing layer to effectively block the light emitted from the display device, the decorative printing layer needs to be thickly formed by alternately overlapping a white printing layer with a printing layer with a decorative color such as black so as to form the decorative printing layer. As pointed out in Japanese Unexamined Patent Application Publication No. 11-66996, when the decorative printing layer is thickened, an air gap is more likely to be formed in a surface base material where the decorative printing layer formed and an adhesive layer to which the base material is adhered therebelow. When the air gap is formed, due to reflection of light at the boundary surface between the air layer and the base material, there is a problem in that transmittance of the display light from the display device is reduced.
(b) In the case of the electrostatic capacitive input device, when a finger approaches the wiring area positioned in the periphery of the detection area, an electrostatic capacitance is formed between the finger and the wiring pattern and easily becomes the cause of erroneous detection.
Here, in input devices described in Japanese Unexamined Patent Application Publication Nos. 2009-169720 and 2005-337773, by covering the disposition area of the wiring pattern, it becomes difficult to cause erroneous detection when a finger approaches.
However, in the device described in Japanese Unexamined Patent Application Publication No. 2009-169720, the shielding layer is formed of the same ITO transparent conductive film as that of an electrode pattern. Since the shielding layer formed of the transparent conductive film remains in a wide range in the periphery of the detection area, in order to form the wiring area, an insulating layer is formed on the surface of the shielding layer, and the wiring pattern is disposed on the insulating layer. Due to the structure in which the insulating layer is interposed between the shielding layer and the wiring pattern, the structure of the input device becomes complex, resulting in an increase in the thickness.
In the device described in Japanese Unexamined Patent Application Publication No. 2005-337773, the disposition area of the wiring pattern is covered with a shielding member formed of a metal plate or the like. Since the shielding member is formed of the metal plate, a reduction in the thickness of the input device becomes difficult, resulting in an increase in the weight.